The Oscar-winning Cold Mountain actress wiped away tears as she took the stage to a sustained standing ovation Tuesday night following the film’s premiere at the Canadian city’s Princess of Wales Theatre: “Okay quit it! You’re messing up my makeup!” the 50-year-old joked.

Zellweger leads the film — adapted from Peter Quilter’s musical End of the Rainbow —as the ill-fated icon who, in the final months of her life, headlined several sold-out shows at London’s Talk of the Town nightclub while grappling with her fraying family life (and substance abuse) between 1968-69.

“It’s a different sense of responsibility that you feel to represent things as accurately as you can by digging through the historical and public record of the legacy of Judy’s life,” Zellweger told the audience after the screening. “In reading those things and considering the source, I learned a little bit about the [difference] between the person’s true history and the public account, and tried to find the balance in between.”

That led her (and costar Finn Wittrock, who plays Mickey Deans, Garland’s fifth husband) on a treasure hunt, “mining” beyond the public facade to find a respectful “celebration” of the woman beneath the surface. That process also included Zellweger forcing herself to dig deep into her own trove of talents — many of which she was apprehensive to explore.

“I couldn’t sing those songs, initially, because I didn’t have the strength to do it,” admitted Zellweger of the film’s challenging soundtrack, which was partially recorded at the famous Abbey Road Studios. Goold further praised Zellweger’s voice, telling moviegoers the actress sang most of the film’s songs live on set as the production filmed.

Experiencing just a fraction of what Garland endured during the final stages of her life gave Zellweger a new appreciation for the superstar, who died from an accidental drug overdose in 1969 at age 47, shortly after her London concerts wrapped.

“I’m sad to say that I took her for granted, like a lot of people you love in your life, she was just always there,” the actress said. “Of course she was extraordinary and deserved that place in history she carved out for herself among the greatest of all time, but it wasn’t until we did this film that I properly came to appreciate how truly extraordinary she was by learning about the circumstances she was grappling with in the third chapter in her life.

“It’s one thing to be born with this God-given mix of talents that are one in a million years,” she continued. “But it’s quite another thing to carry on and navigate your [life] around difficulties. Learning about that and watching this is what sets her apart, it’s not just iconic, but heroic, really, and I was falling more deeply in love the more we learned about her as we went through.”